This invention relates generally to the field of bone osteosynthesis fixation devices, often referred to simply as bone plates, that are used to join two disconnected bone pieces, as well as associated devices or accessories. More particularly, the invention relates to holders or mounts for bone plates and bone screws, as well as to guide devices for properly locating and orienting the bone screws relative to the bone plate and the bone.
In certain operations, such as for example a craniotomy or a cranioplasty, the surgeon drills one or more holes or removes a portion of the skull to expose the brain. At the end of the surgical procedure, the removed portion of the skull is replaced and then secured to the surrounding bone material by mechanical fastening means called bone plates or neuro-plates. The bone plates extend across the kerf or gap between the skull and the removed portion, across the bone holes themselves, or across both. The plates are relatively thin, laterally extended, rigid members that are sized to span the junction between the skull flap and the cranium. Each plate contains at least two and preferably more than two screw-receiving apertures to receive preferably self-tapping or self-drilling screws, the screws being rotationally driven into the bone material comprising the cranium and flap to secure the bone plate in place. Other types of mechanical fasteners, such as rivets or tacks for example, may also be utilized. Bone osteosynthesis fixation devices may also be required in other anatomical locations, such as for example on the jaw, chin, spine or long bones. Bone plates may be of many varied configurations, such as for example, linear, curved, T-shaped, Y-shaped, triangular, rectangular, square, circular or disk-shaped. The particular configuration required is dictated by the location and type of the bone pieces to be joined.
The bone plates are usually relatively small dimensionally, and the bone screws for affixing the plates to the bone material are very tiny. For example, a representative bone plate used in cranial applications can be only about 2 cm in diameter and will be affixed with bone screws less than 5 mm in length. Because of this, handling the bone plates and screws during the fixation procedure is often difficult. The bone plates must be properly located by the surgeon and held in place by forceps or the like while the tiny screws, also held by forceps or retention means incorporated on the driver means, are inserted into screw apertures on the bone plate and then driven into the bone material. It is not uncommon for screws to be lost or dropped during this procedure, which then requires re-sterilization of the screws or replacement. In a worse case scenario, the screws may be dropped into the exposed surgical region where recovery may be difficult. Another problem with current methodology is that the screws may driven into the bone material at improper angles, reducing the effectiveness of the fixation or resulting in improper seating in the bone plate.
It is an object of this invention to provide a holder device that addresses the problems associated with known bone plate and screw fastening systems, wherein the holder device provides a means to temporarily retain both the bone plate and the bone screws during the affixation procedure, is an easily graspable member, being relatively thick in comparison to the bone plate, and provides screw guide means to insure that the screws or other type fasteners are properly oriented when inserted into the bone material.